This invention relates generally to refrigeration systems, and has particular reference to a novel construction for refrigerated containers and trailers.
At the present time, most intermodal refrigerated containers and refrigerated trailers use polyurethane or a similar type of insulation in the walls, ceilings and floors. Normally, the layer of polyurethane must be approximately three inches thick to provide the insulation required. Since the amount of available space for the refrigerated product is very important to users of the containers and trailers, it will be apparent that a reduction in the thickness of the container walls, ceilings and floors without sacrificing the quality of insulation would be desirable. The present invention is directed to this objective and achieves a substantial thickness reduction through use of vacuum as the insulation medium.
The applicant is aware of the fact that vacuum insulation has previously been utilized in refrigerated train cars as is evidenced by U.S. Pat. Nos. 1,237,146 to J. J. Armstrong and 1,246,817 to C. C. Jones, these patents representing the closest prior art known to the applicant. The present invention is believed to be a marked improvement over the Armstrong and Jones constructions as will become apparent as the description proceeds. Other pertinent prior art, developed in the course of a preliminary search, is disclosed in U.S. Pat. Nos. 1,278,529; 1,330,361; 1,984,261; 2,229,079; 2,229,081 and 2,381,796.